I think I played my first piece by François Couperin when I was five years old. It must have been in the exam books of the Royal Conservatory of Music in Toronto, whose Grade One I had passed the year before. My parents, my first teachers, no doubt told me something about him: my father was an organist and taught Couperin's organ works to many of his students.

It was 30 years later that I encountered Couperin seriously again. The manager of my record company, the late Ted Perry, suggested I look at his music. His reasoning was logical: I was coming to the end of a complete JS Bach cycle on disc (played on the piano), so why not look at the French harpsichordists of the period? After all, people play Handel and Scarlatti on the piano, but rarely Couperin and Rameau. So I got the scores to all 234 keyboard pieces by Couperin and began reading them.

It was a daunting task. Some were obviously pure harpsichord material; others were written for two players at once. His 27 suites, or " Ordres " as he called them, all contain between four and 24 miniatures. At the start, I thought I would be lucky to find enough material for one disc, but I gradually fell in love with the music. I now perform it often, and plan to record three discs, including eight complete Ordres.

Born in Paris in 1668, Couperin was a member of a musical dynasty, unique in France and only surpassed in the history of music by the Bach family. A succession of Couperins held the post of organist at the church of Saint-Gervais in Paris for 173 years (1653-1826).

Although the family origins were rustic (Couperin's great-grandfather was a farmer in Brie as well as a music teacher), the Couperins became well-known at the court of Louis XIV, holding posts as organist of the Chambre du Roi and, in François's case, also teaching harpsichord to the dauphin and other royal children.

To fully understand his music, we have to relate it to the manners and habits of the reign of the Sun King, and most importantly to the dance. Fluency and grace in movement, gesture and deportment were part of a general education, especially for the nobility.

Indeed, it is said that Louis XIV practised the courante for several hours a day in his youth. France led the way in dance music, thanks to the operatic ballets composed by Jean-Baptiste Lully (1632-87) and performed at Versailles. In that domain, it made its largest contribution to the history of 17th-century music, and had a huge influence on other composers, including Bach.

As a dancer myself throughout my childhood, I am drawn to any music that is dance-like. In Couperin, I also find the lyricism and poetry that, as a player, I love to express ( Les Langueurs-Tendres is a beautiful example of Couperin's long, expressive lines).

There is more to it than that, however. Most baroque keyboard composers were content to write with minimal ornamentation, phrasing, tempo markings and other clues to interpretation, hoping that the "good taste" of the performer would take over.

Couperin often found that it did not, and became irritated by poor performances of his music. So he became very scrupulous with his markings, and even published a treatise, L'Art de Toucher le Clavecin (The Art of Playing the Harpsichord), that remains one of the most valuable guides on teaching keyboard skills ever written.

One problem facing the modern interpreter is deciphering his ornamentation and markings and making them work. On the piano this is even more difficult because its action is more cumbersome than the harpsichord's.

Woe betide the interpreter who thinks he knows better than the composer, who says: "I am always surprised, after the pains I have given myself for marking the ornaments which are suitable to my Pièces... to hear persons who have learned them without heeding my instructions. This is an unpardonable negligence, the more so since it is not at all an arbitrary matter to put in what ornaments one wishes. I declare that in my pieces they ought to be played as I have marked them, and that they will never make a certain impression on persons of true taste, unless they have observed to the letter everything that I have marked, without adding or subtracting anything."

That is a strong warning indeed, yet how right Couperin is to insist on this point.

Ornamentation is the very essence of his music. It serves an expressive purpose, emphasising one note, making you wait for another, all relating once more to gesture and mood. It takes a long time to absorb it naturally into the interpretation of a piece, let alone to memorise it.

Another thing that immediately strikes us when we open a volume of Couperin's harpsichord pieces is the fanciful use of titles, many of which seem completely baffling. What on earth does Le Tic-Toc-Choc ou les Maillotins mean? Or Les Baricades Mistérieuses ?

I have found internet chatrooms discussing the various possibilities of the last: some think it alludes to the player's two hands "barricaded" in the lower half of the keyboard; a recent book by Jane Clark and Derek Connon says it has something to do with a divertissement called Le Mystère played to relieve a duchess's insomnia. I have even heard it explained as "ladies' underwear" or, to be more precise, "chastity belt". Couperin left no clues and asked to be forgiven for not explaining.

Many are musical portraits of friends, court acquaintances or the King himself. Others, such as Les Moissonneurs (The Reapers) hark back to his rustic origins. One of his most picturesque compositions is Le Rossignol en Amour (The Nightingale in Love), although, as another French composer, Olivier Messiaen, an ardent bird-lover, noted: "I think that Couperin, given what he wrote, never heard a nightingale, but this takes away nothing from the charm of the piece."

Couperin's music is tinged with melancholy - perhaps due to his declining health, which seems to have bothered him for the last 20 years of his life, or perhaps brought on by the disappearance of his son, who disowned his parents (we do not know why).

It is also full of wit, charm and humour, and these very French characteristics make it immediately appealing. Playing his music means immersing oneself in a large cast of characters and trying to find the secret to each one. Sentiment rules over thematic discourse.

I find it fascinating how this music obviously influenced Bach, who admired Couperin enough to copy one of his pieces (Les Bergeries) into a notebook for his wife, Anna Magdalena. The two never met, although there is some record of a correspondence which evidently ended up as jam pot covers, thus lost forever.

The similarities between Couperin's Eighth Ordre and Bach's Overture in the French Style are too many to be pure coincidence. Couperin is a composer whose work pianists and music-lovers should know and understand, not just for its importance in the history of keyboard music, but for sheer pleasure and delight.

· Angela Hewitt's Couperin - Keyboard Works Volume 1 is out now on Hyperion.